Tobacco product and method of manufacture



Patented June 3, 1952 TOBAGQQ PRODUCT AND METHQB OF MANUFACTURE Walter G. Frankenburg, Millersville, Pa., assignor to General Cigar- 60 Inc., New corporation of? New York York, NrY a.

No Drawin Application. June 13, 1947; Serial ,595

1% Claims. 1.

This invention relates to tobacco products adapted for smoking, and moreparticularly to products comprising tobacco in commi-nutedform.

The manufacture of cigars'has reached a; high state of development. Today, even a popularpriced cigar requires the careful blending of as many as fifteen to twenty different types and grades of tobacco. In spite of the great advances which have been made in the desig-nof-automatic machines, the making of cigarsis still characterized by a large proportion of worlcw-hich limits the rate oi production and adds considerably to manufacturing costs; Similarproblems arise in'th-e manufacture of cigarettes-and pipe tobaccos.

In copencling patent application, Serial No. 720,682, of Frankenburg andGarbo, filed: January 7, 1947, now abandoned favor oiE'conti-n-uation application, Serial No, 141,357, filedJanuary 30,-, 1950, now Patent No. 2,592,553, thereis disclosedia process for preparing coherent masses of com.- minuted tobacco, by mixing the comminuted to;- bacco with a, limited quantity of an aqueous solution of awater-soluble derivative of'cellulosaparticularly an ether of-cellulose like methyi-cellulose or carboxymethyl'cellulose to form a paste which is pressed or rolled into sheets,, roc l s.and the like. The thus formed coherent masses of'tjobac'coare then dried and are ready for utilization inci'gar! making machines r any o her desiredimanner. It'hes been f nd tha he e obacco products tend to be somewhat. bri le andto have imited t s st ength- Acco ngl in some cases...- as n t bacco sheets p par d y he process. on the p d ns ppli ation are. fed to a machine utilizing these sheets the. plac .v of the; usual binder, leaves for ci ar diflicul ies. are encountered in that the sheetsfrequentlx tearor rupture and thus interfere withthe Qontinumis:operation of the machine.

The present. invention. is. in the. nature Qt. an. improvement. of. the proce sand productsof. the. aforementioned. copending. application...

The primary object of this. invention-is taproduce from comminuted tobacco. coherentmasses of improved physical properties. without impairs ment of the smoking qualitiesot the tobacco;

In accordance with. this invention,.,lcai tobacco.- which has been processed bydry-ins. curing sweating, fermenting, aging; and. similar treat ments p pa a o y to.-i-ts utili ation n themanufacture of cigars and iik prociuets ee mmiauted. in any'of several well knowo true o or pulverizers. The tobacco.v whiclsmarr inc ude stems. and. midrihs. is generally" atom? to such a degreethat allot the particles will pass through a 20-.mcsh screenand a substantial portion will have a particle size corresponding to the openings of a 40-mesh screen. Considerably coarser and finer tobacco powders are, however, utilizable for the purposes of this invention. The comminuted tobacco is thenconver-ted'into a plastic mass by thoroughly mixing the dry powderwith a limited quantity of a highly-viscous aqueous solution; of a water-soluble derivative of cellulose.

The quantity of aqueous solution of cellulose derivative which is admixed with the powdered tobacco is limited to that which yields a plastic mass having a consistency approximating that of a good neat cement mortar. An excess of solu tion detectable by the tendency of the plastic mass to exude liquid shouldbe avoided since any substantial loss of liquid; reflects a loss of ex-.

tractable constituents inthe tobacco and consequent alteration of the original smoking qualities of th tobacco. Even when soluble consti tuents are extracted from powdered tobacco with water-and the extract is not permitted to-become-separated from the tobacco paste, impairment of the original properties of, the tobacco occurs apparently because. the solubleconstituents undergo undesirable reactions while in the extractform; the; viscous, aqueous: solutions of cellulose derivatives used this; invention. are; such poor: extracting liquids: that: the ordinary injury to! tobacco from. Contact; with. water is largely: ayer edr. Usually,v one part by weight. of comminuted tobacco and, about; two; to six parts vby weight: of: the; aqueous solution of; cellulose deriva:v tive willform a paste ofrthe desired consistency.

The plastic mass. of tobacco is. rolled out. into sheets: or otherwise pressed or formed into desired shapes, e. g-., extruded as a rod or ribbon. Thethus formed coherent mass of tobacco, with or without-prior evaporation of the contained'water, is treated with any of a' wide variety of, substancescommonly referred to as tannins. It is advantageous to select tannins which are derivatives of pyrogallol or cateehol. extracted from the barks. iru-itsi woody parts. root's-and: leaves of many plants; such as valonia, myrobalan, oak, chestnut, sumac, quebracho, mimosa, hemlock and: catechu. Synthetic tanins. which also contain polyhydric phenols. as thezaotive ingredientsv may be used inaceordance with. this invention.

When the tannin in finely powdered. formit. may be. applied to the moist surfaces, or the termed plasticmassofy'tobaoqo by a, simple dusts- As. known. tannins: are:

to any desired moisture content;

1 radical and the solubilizing radical; mul'a; 'n'is a number corresponding to the number 1 cf celluloseunits in the particular cellulose used,

. r is a number not greater than 3 depending upon j the number. of hydroxylgroups in the cellulose unit replaced by ether-linkedsolubilizing radicals i j and Q is'a radical containing 1 to 4 carbon atoms, 7 1 preferably 2 carbon atoms. 1 radical Q containsZ or more carbon atoms, the j more oxygenatoms there are inthe radical Q, 7 the better it is for the purposes of this invention; 1 oxygen. present in the form of --O-I-I groups is particularly, desirable. I soluble derivativesof cellulose successfully ,used; 1 in this inventionare: f V V Methyl cellulose (C6H1Oz(OH) 3- 1) 11- (O'CH3)::1

carboxymethyl cellulose j Hydroxyethyl cellulose H i 1 ing operation. If the tobacco sheet or otherwise shaped mass has already been dried, a solution of the tannin may be sprayed or brushed on the surfaces of the mass. 7

' In order ,to develop more fully the favorable with the result that the cellulose derivative effect of'tanninspn coherent masses of tobacco 1 in whicha water-soluble cellulose derivative' acts as the binding agent it has been found advan 'tageous to expose the tannin-treated mass to a I humid atmosphere for a period of at least twelve 1 hours. It is thought that during'this'period desirable slow reactions between the tannins and 3 ingredients of the tobacco mass aswell-asperhaps oxidation and polymerization'of the tannins i occur, and that these reactions lead to the ob-. 1 served improvements in physical properties of I the coherent tobacco masses. After the tannin treatment, the sheet oroth'er formed may comprise solubilizing radicals which are polymeric in structure.

molecular units each containing 1 to 4 carbon atoms incontrastto a single molecular unit, for instance, the single unit -CH2-CH2OH shown above in the formula for hydroxyethyl cellulose. Water-soluble derivatives of cellulose in which the solubilizing radicals have a polymeric structure are useful for the purposes of this invention.

' Where the water-soluble derivative of cellulose has auacid' grouping as in the case of carboxy- ;methy l cellulose, it may be used in the form of coherentform of comminuted tobacco is dried,

The water is evaporated; at moderate temperatures usually not exceeding about 50 C. Theresultingcoherent;self-supportingtobacco product may then befed to a cigar-making machine or used in any other desired mariner.

Fromthe foregoing description, it is obvious that the .tobacco has not lost any of its constituents during processing nor has it been subinnocuous'to the smoking qualities of the tobacco; as a; matter of fact, some tobacco connoisseurs iind the tobaccoproducts of this invention milder and pleasanter in smoking than the original tobaccos from which the products are made.

As used in this specificationand the appended claims, the term, water-soluble derivative of cel- Advantageously, such a deriva- (C'isHiOziOI-I) 3-1;) .1- (Oma cellulose radicalsolubilizing radical 1 the corresponding salt, usually the sodium or .potassium salt; the prior statement that the water-soluble derivative of cellulose is composed solely of carbon, hydrogen and oxygen is not intended to .exclude'the water-soluble salts, e. g., alkali'metal salts, of acid-type derivatives of cellulose. At anygiven temperature and concentration, the viscosity of the aqueous solution of a cellulose derivative will vary with the molecular complexity or weight of its cellulose radical (factor n) as well as with the degree of etherification (factor 2:). In the foregoing formulae, the factor n is a convenient means used to indicate the polymeric nature of cellulose.

The invention contemplates the use of mixed Water-soluble derivatives of cellulose not only in the sense of mixtures of twoor more separate and different derivatives but also in the sense of singlederivatives having twoor more different substituents associated with the cellulose. Thus, in accordance with the first'sense, a mixture of equal parts by weight of methyl cellulose and sodium salt of carboxymethyl cellulose may be employed as the binding agent for tobacco prod-' ucts. prepared by the process of this invention. In the other sense, suitable binders are'high viscosity grades of single, water-soluble cellulose derivatives having two or more different substituents, which may be exemplified by a cellulose derivative of the type ofmethyl ethyl cellulose or ethyl hydroxyethyl cellulose. It is well to observe that in a water-soluble cellulose derivative with two or more different substituents not all showing an ether linkage between the cellulose I Generally, when the Representative water:

In the for- I lulose when dispersed in water.

ofthe. substituents need to be substituents or radicals'which exert asolubilizing effect on cel- For example, a mixed cellulose ether might have a relatively small proportion of hexyl radicals servingas one substituent and a relatively large proportion of carboxymethyl radicals serving as the solubilizing substituent. In further connection with the though that the cellulose need not be .heavily substituted to yield a water-soluble derivative adapted for the purposes of this invention, it is interesting to note that the sodium salt. of care boxymethyl cellulose used in the examples presented hereinafter is reported to have only 0.4 to 0.6 carboxymethyl group for each anhydroglucose unit of the cellulose molecule or, in other words, for each cellulose radical of the type 'formula shown hereinafter.

From the foregoing it is clear that cellulose etherswhich are water-solubleandform viscous solutions are particularly'usefulin this-invention. However, the invention is notlimited to such ethers and contemplates the use of any suitable water-soluble cellulose derivative, e. g., cellulose esters made up entirely'of carbon, hydrogen and oxygen atoms.

The success of the novel tobacco products of this invention are attributable verylargely to the use of cellulose derivatives having several critical 7 In other words, the radical Q may be composed of a multiplicity of properties. An index of suitable. water-soluble cellulosederivatives is the. viscosity. In general, a suitable cellulose. derivative is. one yielding a viscosity of at least 1500 centipoises at atemperature of 25 C. when a small quantity thereof. not. exceeding about 5% by weight is dissolved in water, preferably, the cellulose derivative yields. an aqueous solution of equal or greater viscosity when present in only about 2% concentration. These cellulose derivatives not only must. dissolve in water and yield at low concentrations highly viscous solutions but also must be, capable of forming with the tobacco powder a coherent, tough sheet or mass when their aqueous, solutions are evaporated to dryness. The behavior of the cellulose derivative in, solution. facilitates the preparation of the plastic mass containing, the finely divided tobacco as well as the subsequent pressing and shaping of the mass into desired forms. The physical characteristics of the cellulose derivative as deposited from its aqueous solution contribute cohesiveness and flexibility to the tobacco product after; it has been dried and conditioned to a desirable moisture content. That properly chosen watersoluble cellulose derivatives should be so effective in producing coherent, self-supporting masses of powdered tobacco is indeed surprising when it is reflected that the finished tobacco product generally contains less than 20% of the cellulose derivative based on the weight of the tobacco, and frequently less than The preferred tobacco compositions contain about 8% to 15% of admixed cellulose derivative based on the weight of the tobacco.

The smoking compatibility of water-soluble cellulose derivatives and tobacco should be safeguarded by the exercise of care in selecting cellulose derivatives in a state of refinement. The

refined products should be free of any appre-- ciable quantities of extraneous matter containing compounds of nitrogen, sulfur, phosphorus and the halogens; in short, compounds giving undesirable products of combustion or of dry distillation should be avoided.

The quantity of tannin required to improve the physical properties of the tobacco sheet. or other coherent form varies with several factors including the particular cellulose derivative acting as the binding agent, the particular tannin selected and the degree. of improvement desired. In any case, simple trials may be made to determine the optimum quantity of tannin that should be employed. In general, however, the quantity of tannin used will fall within the range ofabout 50% to 150% by weight of the cellulose derivative in the tobacco product.

Iron and manganese salts may, in some instances, be advantageously added to the tannins in limited proportions, usually from about 0.1% to 2% by weight of the tannins. Such metal salts, particularly the iron and manganese salts of citric acid and other organic acids, appear to promote the favorable reactions and effects of the tannins in the tobacco products of this invention.

It is advantageous to add a small proportion of bentonite or other water-swelling clay to themixture of tobacco and cellulose derivative. Generally,'additions ofthe order of 1% to 2% by weight of bentonite, based on the weight of dry tobacco powder used, are recommended. It appears that bentonite on swelling in the wet plastic mass of tobacco tends to form a coherent inorganic skeleton or reinforcing network which improves the physical properties of the final product. Tobacco compositions of this invention containing bentonite or like mineral not. only 8. 1 stronger. i. e., showless tendency to or crumble, but also exhibit improved smoking Characteristics. Moreover, the product burns with a firm, coherent ash. The bentonite tends. to ad.- sorb or filter out undesirable tarry: constituentsand alkaloids of tobacco smoke as is drawn through the unburned portion of the bentonite.- containing tobacco. product.

It is. also sometimes beneficial to use a limited. quantity of a ar-agar, generally not, more than about 5% by Weight, of. the tobacco. It appears that the agar-agar dispersed throughout the. mass of comminuted tobacco as a water solu-- tion forms. a. fibrous structure in the finished to.- bacco product when. the water is expelled byevaporation. This belief is based on the, observation that agar-agar improves the physical properties. of tobacco sheets prepared from finely divided tobacco anda binding agent, e. g., the so-- dium salt of carboxymethyl cellulose.

It is often advisable, where the product of this invention is made in sheet form and is later rolled or bent sharply as in making cigars, that the product contain a plasticizer to increase the flexibility and crackingresistance of the sheet. Additions of glycerine of the order of 2% to 15% by weight, based on the weight of dry tobacco used, to mixtures of comminuted tobacco and aqueous solutions of cellulose derivatives with or without bentonite exert an appreciable plasticizing effect. The presence of glycerine in these amounts in the tobacco product does not lead to the formation of unpleasant or troublesome products of complete or incomplete combustion. In the cigarette industry, glycerine is frequently-used as a humectant inthe tobacco without adverse effects from the viewpoint of smoking. Sorbitol may be substituted for at least part of the plasticizing glycerine.

The water-soluble cellulose derivatives of this invention may also be used in making the highly resilient tobacco sheets or bodies disclosed in another copending application, Serial No. 692,775, of Frankenburg, filed on August 24, 1946, now Patent No. 2,592,554. The latter application teaches that tobacco sheets or like'bodies formed from a paste of comminuted tobacco and a viscous aqueous solution of a suitable binder are more resilient and flexible if fine glass fibers are incorporated in the paste. Fine glass fibers of the order of 0.0002" in diameter resembling silk threads not only inappearance but also in softness and flexibility are employed in the proportion of about 1% to 15% based on the weight of the tobacco; preferably, about 2% to 5% by weight of glass fibers are combined with the fine- 1y divided tobacco. This invention contemplates the inclusion of glass fibers in the tobacco compositions discussed herein.

In the interests of better understanding and greater clarity, illustrative embodiments of the invention are presented hereinbelow in detail. In these examples, which are not to be construed in any restrictive sense, the proportions mentioned are all based on a common weight unit.

Example 1 A viscous solution was prepared by dissolving 12 parts of methyl cellulose (Dow Meth0cel- 4000 C. P. S. type) in 500 parts of water. To this solution were added 5 parts of glycerine and 3 parts of sorbitol. Wisconsin cigar leaf tobacco ground to particles chiefly in the size range of 20 to 40- mesh was mixed with the solution to.

5 of total solids or 2.4% of tannins. 1 ment introduced 7.2 parts of tannins into the sheet. After drying for 24-. hours in room air, the tobacco sheet was found to be appreciably stronger and more flexible than it was before treatment with the tannin solution. Smoking 1 tests revealed thatthe product'had a pleasant 1 aroma and burned satisfactorily.

prepared as described in Example 1. wassprayed with a liquid quebracho extract 3 which had been diluted with water so that the 1 0.05% of manganesecitrate.

practical tests. making machine which utilized the sheets as the form" a'consistnt paste; 100parts of the tobacco 1 powder was used; 'The pasty mass which showed 1 no tendency to exude liquid on standing was i placed on a plate off'polished stainless steel and covered with a sheet of wax paper. aid of a roller, the mass was pressed out between the wax paper and steel plate into a layer about ,4, inch thick. The wax paper was removed and the plastic layer was permitted to dry overnight by exposure to room air (about 25 0.). j air-dried tobacco sheet was painted on both sides with an aqueous solution of, powdered myrobalan With the The extract, the concentration being 4.0% by weight This treat- Example 2 An air-dried tobacco sheet (untanninized) was The sheet total solids content was 10% or the tannin content was 6%. 'The' tannin solution penetrated the tobacco sheet so readily that the spraying was applied to only one face of the sheet, quantity of tannins thus introduced was 16'parts.

The

After drying for 30 hours at room conditions, the

E ara'mple 3 An air dried tobacco sheet (untanninized) was I prepared as, described in Example 1. The sheet was sprayed on one side with an aqueous solution containing of wattle extract tannins and The treated sheet had 12 parts oftannin. By comparative tests, it

was shown that themanganese citrate accelerated the tannin reactions so that the sheet could be dried in hours to give a product of the'same Tensile strength measurements were made. on

a plurality of specimens cut from two tobacco I Accordan aqueous solutionof wattle extract to introduce 1 a tannin content corresponding to 75% by weight of the cellulose derivative in the sheet and sheet i B had not been so treated with the tannin solu- 3 tion. The specimens from sheet A had on the average a tensile strength higher than that i of the specimens from sheet B.

These measurements were corroborated by j The sheets were fed to a cigarbinder leaf inthe cigars. During equal operating machine was wasted by breaks and tears while' such failures didnot occur with sheet A.

In addition, the cigars 'made with sheetAas the binder leaf resisted disintegration, when smoked" by cigar-chewers, noticeably better than did'cigars containing sheet B as the'binder leaf.:"'

Itiswithinthe purview of this invention to incorporate, where desired, various additives in the coherent mass ofpowdered tobacco; Thus, with certain tobaccos which burn with difliculty, there may be admixed minute amounts, say of the order of 1o% of the weight of the powdered tobacco, of combustion catalysts, such as the finely"dispersedoxides of iron and other"h'eavy metals. Thisjcan be easily achieved either" by adding these oxides, preferably in colloidal'dispersion, to-the aqueous solution of cellulose derivative or by dissolving small amounts of organic salts of iron and other heavy metals in this solution. These salts form the corresponding oxides in a highly dispersed form during the combustion of the smoking product in which they have been incorporated. r

In a similar way, organic substances can be added to the aqueous solutions of cellulose derivatives in order to impart a desirable flavor to the smoke of the resultingtobacco product. In all impart light texture and porosity to the tobacco product. For instance, the addition of diatomaceous earth, advantageously in the proportion of 5% to 10% of the weight of the powdered tobacco,

results in a material of relatively high porosity and low density. With some tobaccos, 7 this favors combustion and a high-aroma content in the smoke. j

In preparing the aqueous solution of cellulose derivative with or without additives, it is sometimes advantageous to add small amounts of wetting agents, such as sulfonated long-chain aliphatic acids or their salts. Wetting agents facilitate considerably the attainment of intimate contact and cohesion between the tobacco particles, the additives and the cellulose derivative which may be brought togetherin accordance with this invention. Generally, the amount of wetting agent which is eflective is very small; a desirable range of wetting agentadditions covers from 0.01% to 0.10% of the weight of water used in the aqueous solution of cellulose derivative. In such small amounts, the sulfur usually associated with the wetting agent is present in too low a concentration to have any sensible effect; appreciable concentrations are, of course, to be avoided as hereinbefore mentioned.

The present invention is not to be confused with the many suggestions made in prior patents .of which a large number. issued during the period of 1860 to 1900. I These prior proposals generally treated waste tobacco in substantially the same way in which wood, rags, straw, bagasse, etc., are pulped in the manufacture of paper. Some of the later patents acknowledge that the tobacco so converted to paper had lost practically all of, the constituents which make tobacco suitable for smoking,'and attempted to correct this deficiency by impregnating. the tobacco paper with a concentrated decoction obtained by' boiling a suspension-of tobacco in water. However, all of these earlier schemes failed-because it was not appreciated that tobacco and tobacco extracts are inherently delicate and unstable and that even moderate variations in such factors as temperature and hydrogen-ion concentration may adversely effect the tobacco extracts by causing decomposition, oxidation, polymerization or other chemical reactions of the compounds in tobacco. In contrast to these prior unsuccessful efforts, the present invention involves the 'mildest conditions of treatment and avoids the pulping of the tobacco in water or other processing liquid which would extract many soluble tobacco compounds and thus leave an impoverished and deteriorated tobacco product. 1

While the invention is particularly suited for homogeneously blending several tobaccos in a to a' form more uniform in quality .and more adapted to mechanical production of cigars and the like. Whether one or several tobaccos are comminuted and made into the products of this invention, the savings in manual labor and tobacco as well as the improvement of smoking properties cannot be overemphasized.

It should be observed that while the products of this invention are made up of comminuted tobacco and a water-soluble cellulose derivative acting as hinder, the finished products ultimately have thewater-soluble cellulose derivatives in an insolubilized state because of reactions with the tannins and possibly other substances in the coherent tobacco masses. For instance, a tobacco sheet, prepared by mixing powdered tobacco with a viscous aqueous solution of the sodium salt of carboxymethyl cellulose to yield a consistent paste and by rolling the paste out into a thin layer, may be insolubilized by contacting the wet layer with both a tannin and a polyvalent metal salt, e. g., a calcium, aluminum or magnesium salt, and by drying the thus treated layer. It is obvious that, after the tobacco product has been compounded and pressed into the desired form, such insolubilization of the watersoluble cellulose derivative used as the binding agent is not detrimental but rather is beneficial because the binding agent will not be redissolved by the saliva of smokers and will therefore better withstand distintegration of the coherent mass of comminuted tobacco.

Those skilled in the art will visualize many other modifications and variations of the invention set forth hereinabove without departing from its spirit and scope. Accordingly, the claims should not be interpreted in any restrictive sense other than that imposed by the limitations recited within the claims.

What is claimed is:

l. A tobacco product adapted for smoking, which comprises a predominant proportion of ry-ground tobacco, a minor proportion, not exceeding 20% by weight of said tobacco, of a water-soluble cellulose derivative originally having a viscosity of at least 1500 centipoises at a temperature of 25 C. when not more than 2% by weight of said cellulose derivative was dissolved in water, and a minor proportion of a tannin, said cellulose derivative and said tannin functioning to hold the particles of said tobacco together as a coherent mass.

2. The product of claim 1 wherein the watersoluble cellulose'derivative is a cellulose ether of the type represented by the formula: 1

wherein Q is a radical containing 1 to 4 carbon atoms, a is a number not greater than 3 and n is a factor indicating the polymeric nature of cellulose.

3 The product of claim 2 wherein the cellulose "other is an alkali metal salt of carboxymethyl to 15% of an "alkali metal salt ofcarboxymethyl cellulose, based on the weight of said dry ground tobacco, said salt originally having a viscosity of at least 1500 centipoises at 'a temperature of 25 C. when not more than 2% by'weight of said salt was dissolved in water, and about 50% to of a tannin, based on the weight of said salt, said salt and said tannin functioning to hold said dry ground tobacco as a coherent, self-supporting mass.

6. A tobacco product adapted for smoking, which comprises dry ground tobacco, about 8% to 15% of methyl cellulose, based on the weight of said dry ground tobacco, said methyl cellulose originally having a viscosity of at least 1500 centipoises at a temperature of 25 C. when not more than 2% by weight of said methyl cellulose was dissolved in water, and about 50% to 150% of a tannin, based on the weight of said methyl cellulose, said methyl cellulose and said tannin functioning to hold said dry ground tobacco as a coherent, self supporting mass.

'7. The improved process of converting tobacco into a physically continuous and coherent form adapted for smoking, which comprises drygrinding tobacco, mixing the dry-ground tobacco and a viscous aqueous solution of a water-soluble cellulose derivative in proportions to form a cohesive paste substantially free of exudation of said solution, said viscous aqueous solution having a viscosity of at least 1500 centipoises at a temperature of 25 C., shaping said paste, treating the shaped paste with a tannin, and drying said shaped and. treated paste into a physically continuous and coherent form adapted for smoking.

8. The process of claim 7 wherein the watersoluble cellulose derivative is a cellulose ether of the type represented by the formula:

wherein Q is a radica containing 1 to 4- carbon atoms, :0 is a number not greater than 3 and n is a factor indicating the polymeric nature of cellulose.

9. The process of claim 7 wherein the watersoluble cellulose derivative is an alkali metal salt of carboxymethyl cellulose.

10. The process of claim 7 wherein the Watersoluble cellulose derivative is methyl cellulose.

1.1. In the manufacture of smoking products, the improvement which comprises dry grinding tobacco, mixing dry-ground tobacco with a quantity of a viscous aqueous solution of a watersoluble cellulose derivative sufficient to form a cohesive paste but insufficient to permit exudation of solution from said paste, said viscous aqueous solution having a viscosity of at least 1500 centiposes at a temperature of 25 C., pressing said paste into a thin layer, applying a tannin to the surface of said layer, and drying said layer to a coherent sheet.

12. The process of claim 11 wherein the water'- soluble cellulose derivative is sodium carboxymethyl cellulose. p 1 7 13. The process of claim 11 wherein the watersoluble cellulose derivative is methyl cellulose.

- 14. In the manufacture of smoking products,

the improvement which comprises preparing a cohesive and substantially non-exuding .paste comprising dry-ground tobacco, not more than about 15% of a water-soluble cellulose derivative 1 based on the weight of said tobacco, and water, said cellulose derivative and water forming an 1 aqueous solution having a viscosity of at least 7 1500 centipoises at a temperature of 25 C.shap- REFERENCES CITED, The following references are of record in the file of this patent: V

I V UNITED STATES PATENTS Number Name Date 21,558 Durell Sept. 21, 1858 64,591 Stayman May 7, 1867 160,138 Appleby Feb. 23,1875 1 189,182 Broseker Apr. 3, 1877, 591,129 Gerold Oct.5, 1897 2,180,152 Kohler Nov. .14, 1939 2,307,088 Whiteley, Jan. '5, 1943 2,327,991 Betts Aug. 31, 19 3 2,483,877 Wellset al. Jan. 6, 1948 FOREIGN PATENTS Number Country v Date I 879,939 France Mar. 9, 1943 OTHER REFERENCES TheManufacture of Pulp 8: Paper, vol. IV, 3 pp. McGraw-Hill 2d edition, 1928. 

7. THE IMPROVED PROCESS OF CONVERTING TOBACCO INTO A PHYSICALLY CONTINUOUS AND COHERENT FORM ADAPTED FOR SMOKING, WHICH COMPRISES DRYGRINDING TOBACCO, MIXING THE DRY-GROUND TOBACCO AND A VISCOUS AQUEOUS SOLUTION OF A WATER-SOLUBLE CELLULOSE DERIVATIVE IN PROPORTIONS TO FORM A COHESIVE PASTE SUBSTANTIALLY FREE OF EXUDATION OF SAID SOLUTION, SAID VISCOUS AQUEOUS SOLUTION HAVING A VISCOSITY OF AT LEAST 1500 CENTIPOISES AT A TEMPERATURE OF 2K* C., SHAPING SAID PASTE, TREATING THE SHAPED PASTE WITH A TANNIN, AND DRYING SAID SHAPED AND TREATED PASTE INTO A PHYSICALLY CONTINUOUS AND COHERENT FORM ADAPTED FOR SMOKING.
 11. IN THE MANUFACTURE OF SMOKING PRODUCTS, THE IMPROVEMENT WHICH COMPRISES DRY GRINDING TOBACCO, MIXING DRY-GROUND TOBACCO WITH A QUANTITY OF A VISCOUS AQUEOUS SOLUTION OF A WATERSOLUBLE CELLULOSE DERIVATIVE SUFFICIENT TO FORM A COHESIVE PASTE BUT INSUFFICIENT TO PERMIT EXUDATION OF SAID SOLUTION FROM SAID PASTE, SAID VISCOUS AQUEOUS SOLUTION HAVING A VISCOSITY OF AT LEAST 1500 CENTIPOSES AT A TEMPERATURE OF 25* C., PRESSING SAID PASTE INTO A THIN LAYER, APPLYING A TANNIN TO THE SURFACE OF SAID LAYER, AND DRYING SAID LAYER TO A COHERENT SHEET. 